The Ogre Transformation is quite different from the Demon or Ghost Transformations. Ogres aren't otherworldly beings. They belong to this world. A few different rules apply. For one, you cannot transform back. You will be transformed back at the end of the combat round, of course, but until then: You're an Ogre. That's because Ogres are - well - they're stupid. While transformed the magician will no longer have the smarts required to perform a Transformation.
Ogre have no compili... comlicat... difikult martiel ahts. And majic stupid because fire and ice is scary. And Ogre don't need no weapn or such. Ogre have club. Ogre like club. Calls it "Betty". Betty smash good.
While being dumb could be considered a disadvantage, there are also certain advantages. This one transformation does not consume Chi. Ogres wouldn't know what that is, anyway. Just like other Transformations the player cannot heal while being an Ogre. But this too is offset by an advantage: Ogres are able to regenerate their Health. By investing a few style points their regeneration rate can even be increased.
Transformation Style Immunizes against Support Styles and Magic, but not against Fire and Ice. Does *not* Drain Chi Ogres are ugly and dangerous, but they are not related to Demons. They are creatures of the same world as human beings. A truly talented magician may be able to transform himself into an Ogre regardless, but certain limitations apply. Ogres are rather unintelligent creatures. While transformed the magician will be no more intelligent than an Ogre's brain capacity allows. And therefore the magician will not be able to transform back or switch to another style while the hostilities last. That disadvantage is offset by a few advantages, though. Unlike other Transformations this one does not consume Chi. The magician will also acquire the Ogre's abilitiy to regenerate himself. With targeted training the regeneration rate can even be increased!